"""
Misc utilities.
"""

from fractions import Fraction
from typing import Union


def ord_(dta):
    if isinstance(dta, str):
        return ord(dta)
    return dta


def make_string(seq: Union[bytes, list]) -> str:
    """
    Don't throw an exception when given an out of range character.
    """
    string = ''
    for char in seq:
        # Screen out non-printing characters
        try:
            if 32 <= char < 256:
                string += chr(char)
        except TypeError:
            pass

    # If no printing chars
    if not string:
        if isinstance(seq, list):
            string = ''.join(map(str, seq))
            # Some UserComment lists only contain null bytes, nothing valuable to return
            if set(string) == {'0'}:
                return ''
        else:
            string = str(seq)

    # Clean undesirable characters on any end
    return string.strip(' \x00')


def make_string_uc(seq) -> str:
    """
    Special version to deal with the code in the first 8 bytes of a user comment.
    First 8 bytes gives coding system e.g. ASCII vs. JIS vs Unicode.
    """
    if not isinstance(seq, str):
        # Remove code from sequence only if it is valid
        if make_string(seq[:8]).upper() in ('ASCII', 'UNICODE', 'JIS', ''):
            seq = seq[8:]
    # Of course, this is only correct if ASCII, and the standard explicitly
    # allows JIS and Unicode.
    return make_string(seq)


def get_gps_coords(tags: dict) -> tuple:

    lng_ref_tag_name = 'GPS GPSLongitudeRef'
    lng_tag_name = 'GPS GPSLongitude'
    lat_ref_tag_name = 'GPS GPSLatitudeRef'
    lat_tag_name = 'GPS GPSLatitude'

    # Check if these tags are present
    gps_tags = [lng_ref_tag_name, lng_tag_name, lat_tag_name, lat_tag_name]
    for tag in gps_tags:
        if not tag in tags.keys():
            return ()

    lng_ref_val = tags[lng_ref_tag_name].values
    lng_coord_val = [c.decimal() for c in tags[lng_tag_name].values]

    lat_ref_val = tags[lat_ref_tag_name].values
    lat_coord_val = [c.decimal() for c in tags[lat_tag_name].values]

    lng_coord = sum([c/60**i for i, c in enumerate(lng_coord_val)])
    lng_coord *= (-1) ** (lng_ref_val == 'W')

    lat_coord = sum([c/60**i for i, c in enumerate(lat_coord_val)])
    lat_coord *= (-1) ** (lat_ref_val == 'S')

    return (lat_coord, lng_coord)


class Ratio(Fraction):
    """
    Ratio object that eventually will be able to reduce itself to lowest
    common denominator for printing.
    """

    # We're immutable, so use __new__ not __init__
    def __new__(cls, numerator=0, denominator=None):
        try:
            self = super(Ratio, cls).__new__(cls, numerator, denominator)
        except ZeroDivisionError:
            self = super(Ratio, cls).__new__(cls)
            self._numerator = numerator
            self._denominator = denominator
        return self

    def __repr__(self) -> str:
        return str(self)

    @property
    def num(self):
        return self.numerator

    @property
    def den(self):
        return self.denominator

    def decimal(self) -> float:
        return float(self)